Blackbodies

• All bodies (objects), no matter what temperature, emit and absorb infrared radiation
• The hotter the body, the more infrared radiation it radiates in a given time
• A perfect black body is an object that absorbs all of the radiation incident on it
• A black body does not reflect or transmit any radiation
• Since a good absorber is also a good emitter, a perfect black body would be the best possible emitter
• A body at constant temperature is absorbing radiation at the same rate as it is emitting radiation
• The temperature of a body increases when the body absorbs radiation faster than it emits radiation
• The temperature of the Earth depends on many factors including: the rates of absorption and emission of radiation, reflection of radiation into space